1. Field of the Invention
The present invention relates to a fluid treatment device. More particularly, in its preferred embodiment, the present invention relates to an ultraviolet radiation water treatment device.
2. Description of the Prior Art
Fluid treatment devices and systems are known. For example, U.S. Pat. Nos. 4,482,809, 4,872,980, 5,006,244 and 5,590,390 (all assigned to the assignee of the present invention) all describe gravity fed fluid treatment systems which employ ultraviolet (UV) radiation to inactivate microorganisms present in the fluid.
The devices and systems described in the ""809, ""980 and ""244 patents generally include several UV lamps each of which are mounted within sleeves extending between two support arms of the frames. The frames are immersed into the fluid to be treated which is then irradiated as required. The amount of radiation to which the fluid is exposed is determined by the proximity of the fluid to the lamps. One or more UV sensors may be employed to monitor the UV output of the lamps and the fluid level is typically controlled, to some extent, downstream of the treatment device by means of level gates or the like. Since, at higher flow rates, accurate fluid level control is difficult to achieve in gravity fed systems, fluctuations in fluid level are inevitable. Such fluctuations could lead to non-uniform irradiation in the treated fluid.
However, disadvantages exist with the above-described systems. Depending on the quality of the fluid which is being treated, the sleeves surrounding the UV lamps periodically become fouled with foreign materials, inhibiting their ability to transmit UV radiation to the fluid. When fouled, at intervals which may be determined from historical operating data or by the measurements from the UV sensors, the sleeves must be manually cleaned to remove the fouling materials. Regardless of whether the UV lamp frames are employed in an open, channel-like system or a closed system, cleaning of the sleeves is impractical.
In open, channel-like systems, the modules comprising the sleeves are usually removed from the channel and immersed in a separate tank containing a suitable cleaning fluid. In closed systems, the device must be shut down and the sleeves are thereafter cleaned by charging with a suitable cleaning fluid or by removal of the lamps in the manner described for the open, channel-like systems. In either type of system, the operator must accept significant downtime of the system and/or invest significant additional capital to have in place sufficient redundant systems with appropriate control systems to divert the flow of fluid from the systems being cleaned.
The system described in the ""390 patent is a significant advance in the art in that it obviates a number of disadvantages deriving from the devices and systems ""809, ""980 and ""244 patents. Unfortunately, the system described in the ""390 patent is ideally suited for use in an open, channel-like system and is not readily adaptable to be used in a completely closed system where the flow of fluid is fed under pressure in a pipe.
Closed fluid treatment devices are knownxe2x80x94see, for example, U.S. Pat. No. 5,504,335 (assigned to the assignee of the present invention). The ""335 patent teaches a closed fluid treatment device comprising a housing for receiving a flow of fluid. The housing comprises a fluid inlet, a fluid outlet, a fluid treatment zone disposed between the fluid inlet and the fluid outlet, and at least one radiation source module disposed in the fluid treatment zone. The fluid inlet, the fluid outlet and the fluid treatment zone are in a collinear relationship with respect to one another. The at least one radiation source module comprises a radiation source sealably connected to a leg which is sealably mounted to the housing. The radiation source is disposed substantially parallel to the flow of fluid. The radiation source module is removable through an aperture provided in the housing intermediate to fluid inlet and the fluid outlet thereby obviating the need to physically remove the device for service of the radiation source. A disadvantage with this kind of closed fluid treatment device is that the seal between the radiation source module and the housing must be broken each time the former is to be serviced. This confers additional cost and complexity to the servicing needs of the device.
Further, FIG. 1 of the ""335 patent teaches a conventional closed fluid treatment device in which the inlet, outlet and fluid treatment zone are not in a collinear relationship with respect to one another. In the FIG. 1 embodiment, the lamp end connections extend out of the housing.
It would be desirable to have a fluid treatment device which can be readily adapted to treat a flow of fluid fed under pressure in a pipe or like enclosure. It would be further desirable if such a device was relatively easy to clean or keep clean during use. It would be further desirable if the radiation source in the device could be serviced while avoiding the problems associated with servicing the radiation source in the device taught in the ""335 patent.
It is an object of the present invention to provide a novel fluid treatment device which obviates or mitigates at least one of the disadvantages of the prior art.
Accordingly, in one of its aspects, the present invention provides a fluid treatment device comprising a housing for receiving a flow of fluid, the housing comprising a fluid inlet, a fluid outlet, a fluid treatment zone disposed between the fluid inlet and the fluid outlet, and at least one radiation source having a longitudinal axis disposed in the fluid treatment zone substantially transverse to a direction of the flow of fluid through the housing;
the fluid inlet, the fluid outlet and the fluid treatment zone arranged substantially collinearly with respect to one another,
the fluid inlet comprising a first opening having: (i) a cross-sectional area less than a cross-sectional area of the fluid treatment zone, and (ii) a largest diameter substantially parallel to the longitudinal axis of the at least one radiation source.
In another of its aspects, the present invention provides a fluid treatment device comprising a housing for receiving a flow of fluid, the housing comprising a fluid inlet, a fluid outlet, a fluid treatment zone disposed between the fluid inlet and the fluid outlet, and at least one radiation source having an arc length and a longitudinal axis disposed in the fluid treatment zone substantially transverse to a direction of the flow of fluid through the housing;
the fluid inlet, the fluid outlet and the fluid treatment zone arranged substantially collinearly with respect to one another;
the fluid inlet comprising a first opening having: (i) a cross-sectional area less than a cross-sectional area of the fluid treatment zone, and (ii) a diameter less than the arc length of the at least one radiation source.
Thus, the present fluid treatment device and method relate to a closed system for treatment of a fluid. As used throughout this specification, the term xe2x80x9cclosed systemxe2x80x9d, in relation to treatment of a fluid, is intended to encompass a system in which the flow of fluid is pressurized and substantially completely contained in an enclosure throughout treatment. Thus, open, channel-like systems are outside the scope of the present invention since, in the operation of such systems the level of water in the channel and/or treatment zone can vary. The source of pressurization of the flow of fluid is not particularly restricted. For example, the pressure can be generated by a pump or by the action of gravity.
Ideally, the present fluid treatment device and method may be used xe2x80x9cin-linexe2x80x9d in conventional water piping. Depending on the particular application, the piping can be up to 4 in. diameter for domestic applications, or 1 ft. to 3 ft. diameter or more for municipal applications.